PROGRAMS - SUMMER 2013

Deadline for Applications
is January 31

* denotes the organizer responsible for participant diversity in the workshop

Physicists are encouraged to apply as individual researchers to work on their own projects at the Aspen Center for
Physics for up to five weeks at any time during the summer. We provide a serene atmosphere to complete work. The individual researcher may also choose to
attend any workshop meetings or chat with other scientists in residence in addition to working on his or her own research.
Click here for more information.

Working groups of between two and six physicists are encouraged. Click here for more information.

May 26 - June 30 Physics of Functional Biological Assemblies: Pushing, Pulling and Sensing Organizers:Ajay Gopinathan, University of California, Merced Fred MacKintosh, Vrije University Jennifer Ross*, University of Massachusetts
David Sept, Washington University

Biology provides many rich examples of complex and adaptive materials. Cellular systems, in particular, pose fundamental challenges that arise from their non-equilibrium nature and their hierarchical structures. Cytoskeletal filaments, for example, that occur in conjunction with motors and associated proteins are extremely versatile and can display a wide range of dynamically self-assembled structures including radially organized filaments, bundles, cross-linked networks, networks of bundles, membrane associated two dimensional networks and even liquid crystalline phases depending on context and function. Cytoskeletal assemblies govern spatial organization within the cell, the production and transmission of forces, serving as physical and chemical links to the external world and serving as a network for intracellular transport. Function in this system emerges from the interplay between the mechanical properties, dynamics, interactions and biochemical regulation of the constituent elements – providing a fertile ground for applying physical principles to biologically relevant problems and for uncovering new unanticipated physics in these active, dynamic and functional materials.

While we have learnt a significant amount about the physics of these systems, the next hurdle is to relate this
more closely to cellular function. We believe the time is ripe to address this challenge by hosting a workshop that can bring together theoretical physicists,
experimental biophysicists and cell biologists. This will enable the identification of current theoretical and computational challenges, as well as key questions
that need to be addressed by quantitative, physics-based experiments. A five-week workshop focusing on the physical basis of function in these remarkable
assemblies should therefore provide a foundation for innovative new cross-disciplinary approaches.

May 26 - June 16 Lattice Gauge Theory in the LHC EraOrganizers:Simon Catterall, University of Syracuse Paul Damgaard, Niels Bohr Institute Anna Hasenfratz*, University of ColoradoYannick Meurice, University of Iowa

The goal of the workshop is to bring together lattice gauge theorists involved in the study
of various non-perturbative aspects of what is called Physics Beyond the Standard Model.
These include alternatives or modifications of the standard Higgs mechanism, supersymmetry,
and electroweak precision tests, all of which require non-perturbative lattice studies. Beyond
Standard Model investigations are a major program at the Large Hadron Collider (LHC),
and given the timeline for the experimental effort at the LHC, this workshop is very
timely. There are two principal ways to search for Physics Beyond the Standard Model; direct
exploration and indirect searches for signals via precision calculations of observables in the
Standard Model. In the former case, lattice gauge theorists have in recent years established
programs to study candidate both composite Higgs theories such as technicolor and also supersymmetric
gauge theories. In the latter case, there is a well established program in the lattice
gauge theory community to provide precision calculations of strong interaction effects in weak matrix
elements. By comparison with experiment such calculations can yield signs of Beyond
Standard Model Physics.

May 26 - June 16 The Origins of Stellar Clustering: From Fragmenting Clouds to the Build-Up of GalaxiesOrganizers:Nate Bastian, Excellence Cluster Universe Diederik Kruijssen*, Max Planck Institute for AstrophysicsMark Krumholz, University of California, Santa Cruz
Steve Longmore, European Southern Observatory

Some fraction of all stars is formed in gravitationally bound stellar clusters, while the remainder originates
in unbound associations. It is not understood which physical mechanisms
generate either result. Recent work indicates that the outcome of the star/cluster formation process may already be set by the
characteristics of the interstellar medium at the onset of gravitational
collapse. If true, this provides a promising ansatz to identify the physics of cluster formation: the conversion of gas into stellar
clusters. With the new generation of observational facilities such
as Herschel, ALMA, Gaia, and JWST, it will be possible to follow the time evolution of the entire star formation process, from the
structure of the interstellar medium and the initial collapse of
giant molecular clouds to the emergence of massive, dense stellar clusters. The insights that will follow from these observations
can be interpreted in the context of galaxy formation and evolution,
allowing an understanding of how the galaxy-scale environment and small-scale star formation events are influenced by each
other.

By bringing together experts in the theory and observations
of the physics of the interstellar medium, star/cluster formation, cluster populations, and star cluster/galaxy evolution, this
workshop is intended to make significant progress in understanding the wide range of scales and mechanisms that govern the
star and cluster formation process. The three weeks of the workshop will include the following themes. Throughout, there will
be a natural focus on how to direct the theory, numerical work, and observations to meet on common grounds.

1)
The current theoretical understanding of star and cluster formation
- How do collapsing giant molecular clouds (GMCs) fragment and convert their gas into stars?
- Which feedback mechanisms halt star formation, and how does the resulting gas expulsion affect the formation of stellar clusters?
- How do the global characteristics of galaxies influence the properties of GMCs and clustered star formation?

2)
Observational constraints on star and cluster formation
- How well can the progenitors of stellar clusters currently be identified in the interstellar medium (ISM)?
- Which observational methods can be used to determine the gravitational boundedness of young stellar structure?
- What do galaxies other than the Milky Way tell us about the variation of stellar clustering with the galactic environment?

3)
Connecting the dots: towards an understanding of stellar clustering
- Where do the small-scale and galaxy-scale physics of star formation meet and how should both be combined in a complete picture of cluster formation?
- How will the recent and upcoming observational facilities enable us to constrain the physics of cluster formation?
- How can we address the variation of stellar clustering with cosmic time?
- What can we learn about globular cluster formation by considering star and cluster formation in the nearby universe?
Click here to link to the workshop's website.--

The goal of this workshop is to bring together observers, theorists,
and experimentalists who study the cosmic infrared background and the
associated dusty starburst galaxies in the universe from today to the
epoch of reionization. Existing facilities such as the Herschel, ALMA,
and ground-based instruments and interferometers have now discovered
large samples of dusty galaxies and are starting to probe their
physical details with multi-wavelength data. These facilities have
begun to provide detailed observations related to gas, dust and stars
of galaxies
during their peak activity which can be used to improve existing
theoretical models of dusty star formation. Future facilities such as
CCAT and LMT will make further improvements in our understanding of
the universe at sub-mm wavelengths. Existing studies with Planck, SPT
and ACT suggest that these dusty galaxies generate an important
secondary CMB anisotropy signal and its characterization would be
crucial for a variety of CMB studies. The preliminary Herschel results
show that sub-mm surveys can identify large samples of lensed sub-mm
galaxies with efficiency close to 100% - thereby providing a wealth of
cosmological information.

June 16 - July 7 The Next Decade of Weak Lensing ScienceOrganizers:Bhuvnesh Jain, University of Pennsylvania Alexie Leauthaud, Kavli Institute for the Physics and Mathematics of the Universe Rachel Mandelbaum*, Carnegie Mellon UniversityLudo van Waerbeke, University of British Columbia

The scientific promise of weak gravitational lensing (WL) has inspired a number of very ambitious observational programs starting in
2012/2013 (KIDS, Pan-STARRS, HSC, DES), and several more to begin in about a decade from now (LSST, Euclid). These surveys will
cover an order of magnitude more sky area than most existing ones (thousands of square degrees of sky rather than hundreds), and
due to the greater statistical power, better control of systematic errors is also required. The WL community therefore must learn as
much as possible from existing data in order to focus its efforts for the next generation surveys, both to reduce the main sources of
systematic error and to develop more sophisticated ways of handling outstanding theoretical issues.

In the past few years,
there has been extensive development in WL theory, observations, and numerical simulations. The field of WL now reaches such a
maturity and level of complexity that future surveys will benefit considerably from tighter connections between the different areas.
We envision a workshop that will establish strong and durable connection between observers who focused on the previous generation
of lensing surveys, those working on the next generation, and theorists. The ultimate goal is to guide the efforts of those working on
the next generation surveys, which will include thorough discussion of ways to minimize and characterize systematic errors (through
hardware, software, and careful survey design) that plagued previous surveys, and development of theoretical techniques to get the
most information from the data while minimizing sensitivity to any residual systematics.

Among the observational
systematics under discussion will be robust measurement of galaxy shapes under realistic imaging conditions; and estimation of
photometric redshifts (line-of-sight distances to galaxies using broad-band photometry) to get redshift estimates for all galaxies,
and the use of spectroscopic surveys for calibration purposes.

Another equally important aspect is data reduction of very
large data sets and data mining, more specifically what future surveys can learn from computer science techniques and high energy
physics to deal with the ever increasing data flow.

Among the theoretical topics of discussion are intrinsic alignments of
galaxy shapes (due to, e.g. local tidal fields - which can mimic a lensing signal); optimal ways to distinguish between dark energy
and modifications of the theory of gravity; and minimization of theoretical uncertainties in the observables, e.g. due to the (currently)
poorly known effects of baryons (luminous matter).

Regarding numerical simulations, the topics of discussion will include
the important question of small-scale modeling of the dark matter power spectrum and its sensitivity to baryonic physics such as
AGN, supernovae winds and other feedback mechanisms.

The workshop will allow a significant amount of time for informal
discussions and the development of new research collaborations.
Click here to link to the workshop's website.

Taken independently, disorder leads to quantum interference and
localization, interactions to Mott and Wigner insulators, and spin-orbit
coupling to topological band insulators. What is the result, however, of
combining topology with interactions and disorder? What is the nature of
new states of matter induced by topology in interacting systems and the
quantum phase transitions between them? How do disorder effects, such as
localization, modify dynamics in interacting systems, and to what extent
does topological protection still apply? Similarly, the effects of
disorder and defects is far from clear in frustrated interacting quantum
systems, which give rise to exotic phases such as spin-liquids, or
Fermi-liquid with incommensurate order. The aim of the workshop will be
to foster discussion of the ideas, experiments and techniques that could
help us overcome these broad challenges.

July 7 - August 4 Mathematics of Superconformal Field TheoryOrganizers:Daniel Freed, University of Texas Gregory Moore, Rutgers University Andrew Neitzke, University of Texas Hirosi Ooguri*, Caltech

Superconformal field theory is a topic of current significant activity in
both the math and physics communities. This workshop has two focal points:
the (2,0)-superconformal field theory in six dimensions and the scattering
amplitudes of N=4 super Yang-Mills theory in four dimensions. These two
subjects have been the loci of dramatic developments in the last few years.
Moreover, there are tantalizing indications that they are actually linked.

Very few interacting quantum field theories
are known in dimensions greater
than four. Doubtless the most fascinating of these is the (2,0)-superconformal field theory in six dimensions,
first conjectured to exist in 1995 based on string theory arguments. The mere existence of the (2,0)-theory
has fantastic consequences for more familiar, lower-dimensional theories. There are deep connections to
pure mathematics as well. Despite the remarkable applications of the existence of the six-dimensional
superconformal theories, there is no systematic construction of these theories from first principles, not
even at a physicist's level of mathematical rigor. Several different approaches have been suggested, but
none has been entirely successful. One goal of the workshop is to bring together people working on these
different approaches to the foundation of
the subject. In particular, recent advances in the mathematical structure of topological and conformal field
theory are likely to play an important role in this endeavor.

N=4 super Yang-Mills is the most
supersymmetric quantum field theory in four
dimensions. Textbook methods for studying the theory make it look
forbiddingly complex, but recently there is evidence from many different
perspectives that the theory has a deeper underlying integrability. This
integrability is visible even in the most basic quantities derived from the
theory: scattering amplitudes. The traditional procedure at weak coupling
via Feynman integrals is forbiddingly laborious. Powerful new methods for
computing these amplitudes both at weak and strong coupling have been
developed over the last few years, combining ideas from all over the map:
twistors, Yangian symmetry, holography, multidimensional residue calculus,
number theory, and cluster algebras. These methods have vastly expanded the
horizon of what can be computed. The answers, moreover, turn out to be
simpler than they have any real right to be. This points to new fundamental
organizing principles---perhaps for quantum field theory in general---an
enticing possibility to be explored in the workshop.

Some of the new mathematical tools used in the computation of perturbative
amplitudes, most notably cluster algebras and cluster varieties, have also
found prominent applications in investigations of the new superconformal
field theories mentioned in the previous section. This suggests that there
are further deep relations between the new insights in (2,0)-theories and the
new methods in computing perturbative amplitudes.

July 21 - August 11 The Milky Way as a Laboratory for Galaxy FormationOrganizers: Kathryn Johnston*, Columbia UniversityAndrey Kravtsov, University of Chicago Constance Rockosi, UCO/Lick ObservatoryMonica Valluri, University of MichiganMark Wilkinson, University of Leicester

Formation of luminous stellar
components of galaxies within the context of hierarchical structure formation remains one of the main unsolved problems
in astrophysics today.

This workshop will bring together observers, simulators, modelers and theorists to focus on how current and future
resolved star surveys of the Milky Way can be used to reconstruct the structure and formation history of the Galaxy in a
cosmological context. The questions addressed at this workshop will include (a) How can detailed stellar dynamical
modeling be used to estimate the density of dark matter in the vicinity of the Sun (influencing direct dark matter detection
experiments on Earth), as well as the global shape and density distribution of Galactic dark matter?
(b) How can the distributions of the kinematics, ages and abundances of halo stars be used to infer the formation history
and structure of the stellar halo(s) and Galactic disk(s)? (c) What does the satellite system of the Milky Way tell us
about the extreme edge of galaxy formation?(d) How have the evolution of the bulge, bar, disk and halo of our
Galaxy altered their individual properties and the relationship between them, and how can our understanding of their
co-evolution inform our understanding of the formation and evolution of galaxies from high redshifts to today? A
significant goal of this workshop is to identify the modeling and simulation tools that need to be developed to
construct dynamical and stellar population models of our Galaxy and its various components from the enormous
datasets that will soon be available from surveys such as APOGEE, LAMOST, Hermes, Gaia and LSST.

The development of optical lattice emulators is among the most ambitious projects ever conducted in atomic physics research. The goal is to use cold atoms in optical lattices to simulate important lattice models in condensed matter physics whose solutions remain unknown so far. In the last few years, there have many significant advances in this effort including "quantum simulations" of the bosonic and fermionic Hubbard models and imaging of atoms in optical lattices. The recent success in producing synthetic gauge fields heralds a new generation of cold atom experiments to study spin-orbit effects for bosons and fermions including all those in solids. In addition, recent successes in cooling rare earth atoms and dipolar molecules to quantum degeneracy provide new classes of systems with extraordinary high symmetry (like SU(N)) systems, as well as with long range interaction. Theoretical studies of cold atoms in optical lattices have also continued to blossom in the last few years. There is an increasing number of studies of new phases in optical lattices. At the same time, numerical techniques have risen to a new height to tackle many optical lattice problems. This flurry of excitement in both theory and experiment is a reflection of the great ambitions of the field: to realize the most novel systems in condensed matter and to create new forms of quantum matter difficult to achieve in solids; to explore new mechanisms for strong interaction and strong correlation (hence superfluids with high Tc/TF) ratio; to realize and to manipulate topologically protected excitations; to manufacture, and to find applications of highly entangled quantum states.
This workshop aims to bring together theoreticians and experimentalists to push forward the frontier of this exciting field.

August 11 - September 1 Implications of LHC Higgs-Like SignalsOrganizers:John Gunion, University of California, DavisHoward Haber, University of California, Santa Cruz Andrey Korytov, University of Florida Laura Reina*, Florida State University

In July 2012, the ATLAS and CMS collaborations announced the discovery of a new boson with properties suggestive of the
Higgs boson of the Standard Model (SM). Since then, additional LHC running has increased the integrated
luminosity by nearly a factor of three. With this substantially larger Higgs data sample, the new analyses of the ATLAS and
CMS collaborations are beginning to provide a comprehensive picture of the production and decay properties of the 125
GeV Higgs-like state in a variety of channels.

Using this data, one will be able to start to differentiate among models of electroweak symmetry breaking. The Higgs signal
could converge towards the SM expectations in all production and decay channels or exhibit significant deviations. In the
atter case, models that incorporate new physics beyond the SM (BSM) will be examined for consistency with the data. The
Higgs signal has profound implications for supersymmetric models, Randall-Sundrum models (with Higgs-radion mixing),
technicolor models, little Higgs models, composite Higgs models, non-minimal Higgs sectors and so on. If there are still
no direct signals of new BSM physics at the LHC, then the Higgs data and its interpretation will dominate theoretical model
building for years to come. Of course, if the LHC discovers additional new particles and interactions beyond the SM, these
discoveries combined with the precision measurements of Higgs properties will significantly constrain models of BSM physics.

The purpose of this workshop is to summarize the experimental situation as of the summer of 2013 and to explore the
implications of the Higgs data for the SM and for models containing one or more Higgs-like scalar particles. A key
ingredient of the Higgs studies will be the improvement of the accuracy of the theoretical predictions that are crucial
for the extraction of the Higgs boson properties from the data.

August 18 - September 15 Dark Matter in Galaxies, the LHC and Direct and Indirect Searches: Are We Near the End of the Road?Organizers:Marcela Carena, Fermi National Laboratory Carlos Frenk, Durham UniversityGraciela Gelmini*, University of California, Los Angeles Jennifer Siegal-Gaskins, Caltech

Identifying the nature of the dark matter (DM) is one of the most fascinating and important problems in contemporary physics, and one whose solution
may well be within reach. The LHC is exploring many models
of new physics that could explain the DM, as well as the direct production of DM. Direct DM searches have provided us with plenty of excitement
related to ’Light WIMPs,‘ and this issue will see further developments soon. Tantalizing hints of DM signals have also appeared in indirect searches,
such as a 130 GeV line in Fermi LAT data and the rise in the cosmic-ray positron fraction measured by PAMELA and
Fermi LAT. Moreover, gamma-ray limits are, for the first time, excluding regions of parameter space for canonical thermal relic
WIMP DM. Recent kinematical data for the dwarf galaxy satellites of the Milky Way combined
with rigorous predictions of the properties of these systems done with a new generation of ultra-high-resolution N-body
simulations, have lead to conflicting evidence: some studies imply that not all is well with the
standard Lambda-CDM model and that warm, rather than cold, DM provides a better match to the dwarf satellite data,
others, however, suggest that baryon effects can change the picture in subtle but important ways.

This
workshop will bring together particle physicists and cosmologists specializing in the issues most relevant for DM detection,
including the DM distribution in galaxies as well as all current collider, direct, and indirect searches for particle DM, to
explore the complementarity of DM search strategies and re-evaluate the observational evidence for and against a variety of proposed DM candidates.

August 25 - September 15 Multi-Component Many-Body SystemsOrganizers:Egor Babaev*, University of Massachusetts Leo Radzihovsky, University of ColoradoJames Sauls, Northwestern University Asle Sudbo, Norwegian University of Science and Technology

Research on the multicomponent systems has increased enormously in
recent years due to a number of experimental breakthroughs. These
include unconventional and multiband superconductors, topological
superfluids and superconductors, spinor Bose-Einstein condensates,
quantum mixtures of fermionic and bosonic cold atoms, quantum magnets
and spin-liquids, and quantum Hall systems, and various
multicomponent gauge theories emerging as effective theories
in various physical context. Multicomponent ordered states often
exhibit properties which have no counterpart in single-component
systems. Despite a diverse range of microscopic origins, at low
energies this broad array of systems can often be described by
emergent many-body theories exhibiting a significant degree of
universality. There are for instance important connections between
topological insulators, quantum Hall physics and the phases of
superfluid 3He as well multi-component cold atomic condensates. This
workshop will provide a forum for many-body experts in a broad range
of areas to interact and exchange ideas on such diverse
multi-component systems.

September 1 - September 15 Astrophysical Mechanisms of Particle Acceleration and Escape from the AcceleratorsOrganizers:Mikhail Malkov*, University of California, San Diego Patrick Diamond, University of California, San DiegoRoald Sagdeev, University of Maryland

Recent progress in observations brings high energy astrophysics to the forefront of particle physics experiments studying fundamental laws.
Cosmic rays (CR), with an energy spectrum extended to 100 EeV, are unique messengers with which to probe the structure and evolution of the universe, dark matter,
neutrinos, and other important phenomena in astroparticle physics and cosmology, possibly including particles that are yet to be discovered. The newest discovery
of the GZK feature at 30 EeV in the CR spectrum bolsters our basic understanding of how the universe works at extreme energies but the observations also pose
new questions about the composition and anisotropy of the spectrum. The workshop will encompass CR acceleration mechanisms in various astrophysical settings
and discuss their radiative and morphological signatures. For more than thirty-five years the diffusive shock acceleration (DSA, aka Fermi-I) mechanism has been
successfully applied to CR production in supernova remnants, gamma ray bursts, active galactic nuclei, and even in the cosmic structure formation shocks. However,
its role in other important phenomena such as magnetic field generation, particle escape from accelerators, their subsequent propagation and interaction with
ambient medium are not fully understood. It is this interaction that results in the emission that it is now measured with unprecedented precision. These
measurements are not always explicable within the standard DSA theory. Therefore, alternative mechanisms, powered by magnetic and turbulence energy,
rather than by the mechanical shock energy, will also be discussed.
* Organizer in charge of Diversity
For more information about the Aspen Center for Physics, call (970) 925-2585 or email acp at aspenphys. org.